ABSTRACT
Vinegar was discovered fortuitously in ancient times when wine stored undisturbed in the open air turned spontaneously into vinegar. The production of vinegar from wine or any other alcoholic source is the result of the microbiological transformation of ethanol into acetic acid, in a process called acetic acid fermentation and the microorganisms responsible for this transformation are known as acetic acid bacteria (AAB). These Gram-negative bacteria are strict aerobes and are characterized by their capability to oxidize sugars, alcohols and sugar alcohols into their corresponding organic acids. AAB are taxonomically affiliated to the family Acetobacteraceae of the Alphaproteobacteria. The toxicity of acetic acid at low pH has been explained by different effects: uncoupling, intracellular pH regulation, anion accumulation, anion carriers, genetic regulation and resistance. The outer membrane of the AAB has characteristic lipid components that are limited to some Gram-negative bacteria. Complementary approach would give insights on the metabolic modifications and genome adaptations occurring in the natural process.
